JPS6322743B2 - - Google Patents

Description

[Detailed description of the invention] [Technical field to which the invention pertains] The present invention relates to a transmission power control device for a satellite communications earth station, and in particular, to a transmission power control device for a satellite communication earth station, and in particular, to This invention relates to a transmission power control device that is incorporated into the same communication network as a station and is applied to earth stations other than this specific earth station.

[Description of prior art]

In satellite communications, particularly in satellite communications that use high frequencies such as sub-millimeter wave bands, radio waves are attenuated significantly by rainfall, and appropriate countermeasures are required to deal with this. Appropriate countermeasures for downlinks from satellites to earth stations include providing the earth station receiving equipment with a margin to compensate for attenuation, or using a site diversity method to eliminate the effects of rain. . On the other hand, for the uplink from the earth station to the satellite, apart from using the site diversity method, it is not possible to use a transmission power with a certain predetermined margin against rain attenuation. This results in unnecessary consumption of transmission power, which is very disadvantageous from the viewpoint of effective use of satellite transmission power. Therefore,
A method of controlling the transmission power from the earth station according to the rainfall attenuation of the uplink has been considered, and this is generally called the earth station transmission power control method.

In this transmission power control method, at least one specific earth station among a plurality of earth stations controls the effective isotropically radiated power (EIRP) of the pilot signal or communication signal within the communication frequency band on the satellite, regardless of rainfall attenuation. A control means is provided to keep the temperature constant.
(See references).

Conventionally, with this method, a pilot signal or communication signal that is controlled so that the effective isotropic radiation power of the satellite is constant is received, and the level fluctuation of this signal or the carrier-to-noise power ratio (hereinafter referred to as "C/N A method of controlling transmission power to compensate for the uplink rain attenuation by estimating the uplink rain attenuation based on fluctuations in the ratio (referred to as "ratio") (see references).

One of the communication signals transmitted from the own station and returned by the satellite or the test signal sent to the communication line, and the pilot signal or communication signal controlled to be constant at the satellite. A method of controlling the transmission power of the earth station by comparing the levels or C/N ratios of the earth stations (see references).

etc. have been proposed.

In the case of the above method, although the scale of the equipment is simple, it does not have any means to detect gain fluctuations in the own earth station transmission system or satellite repeater.
Simply estimating and controlling the gain fluctuations of the transmission system from fluctuations in the reference received signal has the disadvantage that there is no guarantee that the EIRP on the satellite is constant, and it cannot be confirmed.

On the other hand, in the case of the above method, although the control accuracy is satisfactory, each station constantly needs a return signal to its own station, which increases the power consumption of the satellite and requires large equipment at the earth station. There are drawbacks such as:

[Purpose of the invention]

The present invention solves the above-mentioned drawbacks of the prior art, and provides a practically effective satellite communication earth station transmission system that allows sufficient control accuracy to be obtained without increasing the power consumption of the satellite. The purpose of the present invention is to provide a power control device.

[Key points of the invention]

A plurality of earth stations including a specific earth station communicate via a satellite, and the specific earth station receives effective isotropic radiated power from the satellite, which is at least one of a pilot signal or a communication signal within the communication frequency band. In a satellite communication earth station equipped with a control means to keep it constant regardless of attenuation, all or some of the earth stations except the above-mentioned specified earth station are controlled so that the effective isotropically radiated power at the above-mentioned satellite is constant. a first detecting means for receiving a pilot signal or a communication signal transmitted from the station and detecting a level variation of the signal or a variation in a carrier-to-noise power ratio; and a first detecting means for receiving and detecting a satellite return signal of the signal transmitted from the own station. a second detection means, and a switching means for switching the control mode between an estimation mode and a calibration mode at appropriate time intervals; in the case of the control mode, the level or the carrier-to-noise power of the first and second detection means; The transmission power of the earth station is controlled by comparing the ratio, and in the case of the estimation mode, the transmission power of the earth station is controlled based on the level fluctuation of the signal transmitted from the specific earth station among the signals or the fluctuation of the carrier-to-noise power ratio. The present invention is characterized in that the transmission power of the earth station can be controlled by estimating and converting uplink rain attenuation.

Note that, in practice, it is sufficient to switch to the calibration mode several times a day. The calibration mode time is the time required for calibration, and one minute or less is sufficient.

[Explanation based on examples]

Hereinafter, the present invention will be explained based on the drawings.

The figure is a block diagram of an apparatus according to an embodiment of the present invention, and shows a case where a single channel per carrier (SCPC) system is used.

In the figure, the receiving system includes an antenna 1 for both transmitting and receiving;
A low noise amplifier 10, a reception frequency converter 11 that converts a high frequency reception signal to an intermediate frequency, an intermediate frequency amplifier 12 that amplifies the output of this converter 11 and performs AGC (automatic gain control) operation, and a common amplified signal therein. A divider 13 is connected to the output of the divider 13 to detect the pilot signal and output the AFC (automatic frequency control) signal, AGC signal and
A pilot receiver 14 that outputs a signal for TPC (transmission power control), and a group of receiving channel units that are also connected to the distributor 13 and that receive and demodulate communication signals from the other station and send out channel reception outputs (RX OUT). 15 ₁ to 15 _n .

On the other hand, for the transmission system, the channel transmission input (TX IN)
A transmission channel unit group 20 ₁ to
20 _n , a combiner 22 that combines the power of the outputs of these unit groups 20 ₁ to 20 m, a transmission intermediate frequency amplifier 23 whose gain is controlled by a control signal, and a transmitting intermediate frequency amplifier 23 that converts the amplified intermediate frequency signal into a high frequency signal for transmission. a transmitting frequency converter 24 and this converter 24;
The receiving system and the transmitting system constitute a main transmission path.

Furthermore, the transmission power control system is controlled by the pilot receiver 1.
a detector 30 for detecting the output level or C/N ratio of 4, and a group of receiving channel units 15 ₁ to 15 _n
Monitor point of one of the units (refers to the point just before the demodulator that is band-limited to the channel bandwidth)
and a detector 31 for detecting the output level or C/N ratio of the signal obtained from the
A holder 32 that switches the output of the detector 31 to pass or hold state by an external control signal, a comparator 33 that extracts the difference between the detected outputs of the detectors 30 and 31, and an intermediate frequency amplifier 23 that controls the output of the comparator 33. It is comprised of a TPC controller 34 for controlling transmission power that performs signal processing so that the signal is appropriate, and a logic device 35 that performs switching of control modes and the like.

Next, the control operation will be explained. There are two control modes in this method: estimation mode and calibration mode. In the estimation mode, the holder 32 enters the holding state under the control of the logic unit 35, and the detector 3
Since the signal of 1 is separated, only the signal of the detector 30 passes through the comparator 33 and the TPC controller 34, and the operation is to perform estimation control to control the transmission gain from the information of the received signal. However, in this case, as described in the prior art, there is a problem with the accuracy of the control error, so it is not preferable to control in the estimation mode for too long. Therefore, the control mode is switched from estimation mode to calibration mode at appropriate time intervals. In this calibration mode, the logic unit 35 controls one of the transmission channel units 20 ₁ to 20 _n at preset appropriate time intervals to transmit a carrier wave, and also puts the holder 32 in the passing state. By controlling the output of the receiving channel unit tuned to the previously transmitted carrier wave, the output of the receiving channel unit is transmitted to the detector 31 and the holder 3.
The signal is input to the comparator 33 via 2 and 2. In this state, the EIEP of the satellite output is controlled to be constant and the closed-loop control operation is based on the pilot signal, so errors caused by gain fluctuations in the earth station transmission system can be compensated with sufficient control accuracy. Thereafter, the control mode is returned to the estimation mode. Switching between the two modes may be performed manually or automatically controlled by a timer. The period is determined within a range that does not affect communication and in light of the performance of the device. In the case of calibration mode, the channel unit used for communication signals can be used for both transmission and reception, and the interval of calibration mode is several times a day, and the time per time is less than 1 minute. Since it is considered sufficient,
The impact on power usage by earth station equipment and satellites is almost negligible.

The above explanation was based on the case of pre-assignment in which the frequency of each channel is predetermined, but in the case of a demand-assignment system, a logic circuit is used in the demand-assignment multiple access (DAMA) device. By incorporating 35 functions, you can specify any frequency in the calibration mode as in normal call processing, or all the earth stations participating in the system can share a specific frequency and perform the calibration mode in a time-sharing manner. It is also possible to control the process to process the data, thereby further increasing the effectiveness of the present method.

In addition, in the calibration mode, a dedicated carrier wave generator and receiver are prepared and controlled in place of the communication signal transmission/reception channel unit, and the configuration is configured so that there is no effect on normal call processing. It is clear that this is essentially the same as the above explanation.

〔Effect of the invention〕

As described above, the present invention performs transmission power control by repeating the estimation mode and the calibration mode at appropriate intervals, so it can be done without increasing the power consumption of the satellite by adding simple equipment. Sufficient control accuracy can be obtained, and the practical effect is extremely large.

[Brief explanation of drawings]

The figure is a block diagram of a device according to an embodiment of the present invention. 1...Antenna, 10...Low noise amplifier, 11...
...Receiving frequency converter, 12...Intermediate frequency amplifier,
13...Distributor, 14...Pilot receiver, 1
5 ₁ to 15 _n ...Reception channel unit group, 20
₁ to 20 _n ...Transmission channel unit group, 22...
...Synthesizer, 23...Intermediate frequency amplifier, 24...Transmission frequency converter, 25...Transmission power amplifier.

Claims (1)

[Scope of Claims] 1. A plurality of earth stations including a specific earth station communicate via a satellite, and the specific earth station is provided with an effective isotropic radiation power of the transmitted signal of the satellite that is constant regardless of rainfall attenuation. In a satellite communication earth station equipped with a control means to or a first detection means for detecting the carrier-to-noise ratio; a second detection means for receiving the satellite return signal of the signal transmitted from the own station and detecting the level or carrier-to-noise power ratio of the signal; and a control mode. switching means for switching between the calibration mode and the estimation mode at appropriate time intervals; and in the calibration mode, the first detection means and the second detection means
means for comparing the output with the detection means and controlling the transmission power of the own station based on the comparison result; and a means for controlling the transmission power of the own station based on the comparison result; A transmission power control device for a satellite communication earth station, comprising means for controlling the transmission power of its own station by estimating rainfall attenuation.